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tempstar furnaces ????????

John732
John732 Member Posts: 16
Has anyone on here had any issues with tempstar 95% forced air furnace high limit going off and getting a code 4 for no reason. i verified it was high limit, and changed it out and again client is calling saying unit cycling....this is a new furnace and coil done in august. verified secondary heat exchanger clean , coil clean and no blockages, filter clean and a cheapo one ( non restrictive) , temp rise is 56f within range of 40-70 range. total duct static .6 ....only thing is i can do is up fan speed but my temp rise perfect. or try cutting more return. thing that is making me hesitate is duct static not bad and its an ecm motor which can pull easy up to 1 IN. W.C ....return duct size 25 x 8 lined 80kbtu furnace, i think 3 1/2 ton drive blower...question has anyone had problems like this with tempter and everything checks out good.... feed back appreciated

Comments

  • HVACNUT
    HVACNUT Member Posts: 4,873
    Temp rise is within range but what is the actual supply air temperature?

    What are the combustion numbers, specifically flue temperature?

    Natural or LP gas? What's the manifold gas pressure?
    I did a conversion kit on a Rheem furnace today. I had 19.36" wc when it first fired. I backed it out to 10" right quick.

    When you say "coil", I assume you mean evaporator. How much space is there between the top of the coil and the top of the supply duct? Was A/C there before? 

  • pedmec
    pedmec Member Posts: 713
    Are you measuring your static in the right locations. Feels like the motor might be tripping out to protect itself but its happening in midcycle and its showing up as a high limit. did you measure supply and return static and add them together? what size is the supply. set the dip switch for 1400 cfm's.
  • John732
    John732 Member Posts: 16
    To hvacnut its natural gas , i did not take gas pressure i will when i go back but we did a replacement and previous furnace worked so i didnt go down that route as for actual supply plenium temp. it was 141F.(delta t 56f) its a 95% furnace but i did not take flue temp. maybe i should. but flame looks good, its not lazy ,pulling nicely into burner tubes nothing that i would suspect flue issue. we did not change or alter, the pressure switch is pulling well i tested with manometer.....as for PEDMEC yes i did static in right place in return of furnace after filter and between coil (evaporator) and furnace. The coil is a direct fit right on top of furnace ,standard install . i waas told by a few of my friends that tempstar is very sensitive and trips very easy . i verified it was the high limit going off !00%. the high limit is cut out 170f and cut in 20f... i was told other furnaces are usually higher. one thing i did do is take out high limit and measure temperature with my prob. and got 124F which i found odd especially that limit is set for 170F. thinking about adding more return its up for debate just want to check everything else before i spend more money on a job that was complete if i dont have to . also wondering if anyone else has had issues with tempstar furnaces
  • Ironman
    Ironman Member Posts: 7,088
    I’ve had furnaces (including the one that was in my house) that had the disc limit switch located too close to the wall of the heat exchanger. Bending the metal arms that hold the switch fixed the problem.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    John732
  • pecmsg
    pecmsg Member Posts: 3,574
    John732 said:

    To hvacnut its natural gas , i did not take gas pressure i will when i go back but we did a replacement and previous furnace worked so i didnt go down that route as for actual supply plenium temp. it was 141F.(delta t 56f) its a 95% furnace but i did not take flue temp. maybe i should. but flame looks good, its not lazy ,pulling nicely into burner tubes nothing that i would suspect flue issue. we did not change or alter, the pressure switch is pulling well i tested with manometer.....as for PEDMEC yes i did static in right place in return of furnace after filter and between coil (evaporator) and furnace. The coil is a direct fit right on top of furnace ,standard install . i waas told by a few of my friends that tempstar is very sensitive and trips very easy . i verified it was the high limit going off !00%. the high limit is cut out 170f and cut in 20f... i was told other furnaces are usually higher. one thing i did do is take out high limit and measure temperature with my prob. and got 124F which i found odd especially that limit is set for 170F. thinking about adding more return its up for debate just want to check everything else before i spend more money on a job that was complete if i dont have to . also wondering if anyone else has had issues with tempstar furnaces

    Supply plenum was 141°F ?

    IronmanJohn732
  • mattmia2
    mattmia2 Member Posts: 7,216
    It isn't one of those limits mounted on a standoff in the airflow with a piece of foil flapping around and shorting out the limit, is it?
  • Ironman
    Ironman Member Posts: 7,088
    If the supply temp was 141, and the return temp is 70, then that’s a 71* temp rise, not 56*.

    If you actually had a 56* rise with a 141* supply, the return temp would have had to be 85*. Who keeps a house that hot?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    pecmsg
  • JUGHNE
    JUGHNE Member Posts: 10,331
    I had the foil flopping short out the high limit on a furnace years ago.

    But it cooked the power transformer as there was no low voltage fuse.
  • John732
    John732 Member Posts: 16
    IRONMAN....well since we were doing testing and running , my limit kept tripping about 12 minutes , until i pin pointed the limit was opening , at first i thought it was flue issue . so every time the supply went up so did return so yeah my return was 85 .i thought that was weird but that's what thermometer said and returns are on side wall but high near ceiling, it got that way as we keep turning up stat so we could try to run unit to see which limit was tripping. but it basically maintain 56 - 55 td . after changing high limit its not doing any more. so i believe we stopped the cycling. new unit with faulty high limit rare but i was just wondering if that was tempstar issues ?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 13,169
    @John732

    If you measured the discharge temp when stabilized at 141 and the limit is a 170 then obviously the limit is bad. 170 seems low for a limit but it shouldn't get that high anyhow. When your down to a normal return temp you should be around 126
  • pecmsg
    pecmsg Member Posts: 3,574
    John732 said:

    IRONMAN....well since we were doing testing and running , my limit kept tripping about 12 minutes , until i pin pointed the limit was opening , at first i thought it was flue issue . so every time the supply went up so did return so yeah my return was 85 .i thought that was weird but that's what thermometer said and returns are on side wall but high near ceiling, it got that way as we keep turning up stat so we could try to run unit to see which limit was tripping. but it basically maintain 56 - 55 td . after changing high limit its not doing any more. so i believe we stopped the cycling. new unit with faulty high limit rare but i was just wondering if that was tempstar issues ?

    Thats a very High return temperature. Not a normal operating range.
    John732